Chrysoprase

Chrysoprase is the apple-green variety of chalcedony that contains small amounts of nickel. Its colour ranges from yellowish green through turquoise-like blue-green to deep green. Emerald takes its green from chromium, whereas chrysoprase gets it from very fine inclusions of nickel silicates. Unlike most chalcedony, it is its green colour, not a pattern, that makes the stone desirable. It is mined in Türkiye too: deposits are known around Biga, Bilecik, Sivrihisar, Oltu and Savur.

Jewellery and ornaments: cabochons, beads and small objects are made from it. Turkish Wikipedia says the stone has been used in rings and jewellery as cameos or seal stones since before Roman times. Fashion: English Wikipedia notes that chrysoprase was fashionable in the 1980s.

It has a hardness of 6.5–7 on the Mohs scale. It scratches glass and steel; a steel knife cannot scratch it. Its specific gravity is 2.58–2.65 g/cm³.

Its best-known localities: Marlborough, Queensland, Australia; Haneti, Dodoma Region, Tanzania; Szklary, Lower Silesia, Poland; Leonora area (Marshall Pool), Western Australia; Indonesia.

Known localities in Türkiye: Biga, Çanakkale, Türkiye; İkizce, Bilecik, Türkiye; Sivrihisar, Eskişehir, Türkiye; Oltu, Erzurum, Türkiye; Savur, Mardin, Türkiye.

It is apple green and translucent, with a colour that is roughly even throughout the stone; it draws the eye by its colour, not by a pattern. Its hardness is 6.5–7: it scratches glass, and a steel knife cannot scratch it. A broken surface is curved like a shell (conchoidal), as in flint. Dyed chalcedony: because chalcedony is porous it takes dye easily. Very vivid, artificial-looking greens are mostly dyed, and dyeing should be disclosed.

On the “street to diamond” value ladder it sits on step 6 of nine: Fine ornamental and collector stone. The value of chrysoprase depends above all on the vividness and evenness of its colour: a bright, saturated, even apple green is the most sought after. Translucency and freedom from cracks matter too. Unlike most chalcedony, its value comes from its colour, not from a pattern. Dyed chalcedony and chrome chalcedony are not natural chrysoprase, and because the colour can fade with heat or sunlight, the stone needs careful storage.

According to Volmar, a thief sentenced to be hanged or beheaded would escape his executioners at once if he put a chrysoprase in his mouth; Kunz suggests this may come from the belief that the stone made its bearer invisible. Albertus Magnus tells that Alexander the Great wore a stone called “prase” in his girdle in battle, and that a serpent bit the stone off and dropped it into the Euphrates; Kunz calls it a “victory stone”. Christian commentators tied chrysoprase to sacred meanings: according to one writer it stands for the work and the reward of the martyrs, according to another for sternness towards sinners. There is no evidence that chrysoprase saves anyone from execution or brings victory or protection in battle; these are old stories. Kunz notes that medieval writers used the name “prase” very loosely, and that the stone described may have been an emerald or jade. This section reports beliefs; it is not health information. There is no scientific evidence for these claims and no stone replaces medical treatment.